>>That's my daughter's math question. I couldn't solve that... :(
>>
>>f(x/y)=f(x)+f(y)
>>f(10)=1
>>f(10000)=?
>
>Obviously the idea is to find out what the function is. The form of the function reminds me strongly of a logarithm (log ab = log a + log b), except that we have a division here. Are you sure the first part is plus, and not minus?

I asked my daughter again. You right, it was minus. Sorry...